The present invention generally pertains to microwave devices, such as antennas and stubs and is particularly directed to improvements in microwave devices in which resonance at a given microwave frequency is determined by the dimensions of a discontinuity defined by conductive material.
One such device is a microwave slot antenna in which the resonant frequency in a given plane is determined by the length of a slot in a given dimension corresponding to the plane. The slot is defined by a conductive material discontinuity and has a length in the given dimension equal to one-half the wavelength corresponding to the given microwave frequency.
Another such device is a microwave cavity-backed antenna in which the resonant frequency is determined by the dimensions of a cavity disposed in back of a radiating element. A cavity-backed spiral antenna is an example of this type of device. The radiating element is backed by a conductive material structure, such as a cylinder, having boundaries dimensioned to define a resonant cavity at the given microwave frequency.
Still another such device is a microwave transmission line stub including complementary layers of a conductive material each having a branch dimensioned for impedance matching the transmission line at the given frequency, wherein the branches are connected to each other at their extreme ends.